The age or size structure of a population has a marked influence on its demography and reproductive capacity. While declines in coral cover are well documented, concomitant shifts in the size-frequency distribution of coral colonies are rarely measured at large spatial scales. Here, we document major shifts in the colony size structure of coral populations along the 2300 km length of the Great Barrier Reef relative to historical baselines (1995/1996). Coral colony abundances on reef crests and slopes have declined sharply across all colony size classes and in all coral taxa compared to historical baselines. Declines were particularly pronounced in the northern and central regions of the Great Barrier Reef, following mass coral bleaching in 2016 and 2017. The relative abundances of large colonies remained relatively stable, but this apparent stability masks steep declines in absolute abundance. The potential for recovery of older fecund corals is uncertain given the increasing frequency and intensity of disturbance events. The systematic decline in smaller colonies across regions, habitats and taxa, suggests that a decline in recruitment has further eroded the recovery potential and resilience of coral populations.

中文翻译：

---

大堡礁沿岸珊瑚种群规模结构的长期变化


人口的年龄或规模结构对其人口特征和生殖能力有显着影响。虽然珊瑚覆盖率的下降已有充分记录，但很少在大空间尺度上测量珊瑚群落大小频率分布的伴随变化。在这里，我们记录了大堡礁 2300 公里长的珊瑚种群规模结构相对于历史基线（1995/1996）的重大变化。与历史基线相比，珊瑚礁顶部和斜坡上的珊瑚群落丰度在所有珊瑚群大小类别和所有珊瑚类群中都急剧下降。在 2016 年和 2017 年大规模珊瑚白化之后，大堡礁北部和中部地区的下降尤为明显。大型珊瑚群的相对丰度保持相对稳定，但这种明显的稳定性掩盖了绝对丰度的急剧下降。鉴于干扰事件的频率和强度不断增加，较老的繁殖力珊瑚的恢复潜力尚不确定。跨区域、栖息地和类群的较小珊瑚群的系统性下降表明，补充数量的减少进一步削弱了珊瑚种群的恢复潜力和复原力。